Anchoring Interfacial Nickel Cations by Tunable Coordinative Structure for Highly Stabilized Nickel-Rich Layered Oxide Cathodes. (March 2022)

• Record Type: Journal Article
• Authors: Ma, Cheng; Chen, Minjian; Ding, Zhengping; Wei, Bo; Liang, Chaoping; Zhou, Liangjun; Chen, Libao; Ji, Xiaobo; Gao, Peng; Wei, Weifeng
• Is Part Of: Nano energy. Volume 93(2022)
• Publication Date: 2022-03
• Subjects: Nickel-rich layered oxide cathodes -- Highly reactive Ni4+ cations -- Electron-donating organic groups -- Surface coordinative structure -- Interfacial stability; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2021.106803
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: Ni-rich LiNix Coy Mn1−x-y O2 (NCM) cathode materials have received extensive attention on account of their high specific capacities and great application prospects in electric vehicles. While increasing Ni content in NCM can greatly increase initial discharge capacities, more highly reactive Ni 4+ species in the delithiated state may facilitate irreversible phase transformation and undesirable interfacial reactions, leading to severe capacity degradation. Here we demonstrate an organic surface modification approach to modulate the surface coordinative structure of NCM cathode for enhanced cycling stability. We discover that the highly reactive Ni 4+ cations can be anchored by strong electron-donating organic groups, especially under bidentate coordination, which mitigates excessive electrolyte decomposition and Ni dissolution into the electrolyte, inhibits the layered-to-rock salt phase transformation and suppresses the initiation and propagation of microcracks within the NCM cathodes. In consequence, the nickel-rich cathode coated with poly (acetoacetoxyethyl methacrylate) (PAAEM) with multiple ester groups exhibits a remarkable improvement in cycling stability, showing 91.3% retention of the initial capacity after 200 cycles. The present findings demonstrate that regulating surface coordinative structure is an efficient and practical strategy to modify the interfacial reactions for enhanced cyclability in Ni-rich layered oxide cathodes. Graphical Abstract: Anchoring interfacial nickel cations using functionalized polymeric nanolayers shows great potential to stabilize Ni-rich LiNix Coy Mn1−x-y O2 (NCM) cathodes. Compared with monodentate ligand (R−CN − Ni) provided by poly (2-cyanoethyl acrylate), poly (acetoacetoxyethyl methacrylate) with multiple carbonyls groups enables bidentate coordination (R−CO−Ni−OC−R), and is more favorable to suppress the electrolyte decomposition, the layered-to-rocksalt (NiO) transformation and subsequent Ni dissolution and the microcracks formation and propagation within the NCM particles. ga1 Highlights: An organic surface modification approach was well demonstrated to modulate the surface coordinative structure of NCM cathode. The highly reactive Ni 4+ cations can be anchored by strong electron-donating organic groups, especially under bidentate coordination. Tailoring the surface coordinative structure provides a robust strategy to address the issues of capacity/voltage decay of NCM cathode.